This study proposes to examine the effects of continuous evaluation on cognitive development in infants and on the behaviors of mothers involved in the evaluation process. Special attention will be paid to possible mechanisms whereby infant development may be enhanced by maternal participation in the evaluation procedures. The design of this study includes 10 evaluations over the first 30 months of life of 40 infants from low socioeconomic families (less than $4,850 per year net income), 20 with their natural mothers, and 20 accompanied by mothers of other infants (helper mothers). Social, intellectual and adaptive behavior evaluations will be completed on all 40 infants at 30 months of age. In addition the unevaluated infants of the helper mothers, the mothers of the accompanied infants and a control group of 20 mothers and infants will be similarily studied. Comparisons will be made between the 4 groups to study alternative evaluation effects. The continuous evaluations will consist of the Bayley Scales of Infant Mental and Motor Development, Anthropometric Measures, maternal interviews, and observations of infants. All 4 groups will be evaluated when the infants reach the 30th months of age--the infants with the Stanford-Binet, observations of social and intellectual activities, assessment of language and cognitive development, and assessment of social skills. In addition, mothers in all 4 groups will be interviewed for an assessment of maternal attitudes and practices toward child rearing, level of information on child development and observations of mother-child interactions as compared between the four groups